Data Communication with Embedded Pilot Information for Timely Channel Estimation

1. A pilot-embedded data transmission and channel estimation method for a Multiple-Input Multiple-Output (MIMO) communication system comprising the steps of: selecting a data-bearer matrix “A” and a pilot matrix “P” based on orthogonality constraints; allocating respective fractions of a fixed amount of transmission power to said data-bearer matrix “A” and said pilot matrix “P”; converting a space-time codeword data matrix “D” into pilot-embedded data matrix to be transmitted according to said fixed amount of transmission power; transmitting at least one of said pilot-embedded data matrix from a transmitting antenna defining one end of a data channel; receiving at least one of said pilot-embedded data matrix at a receiving antenna defining an opposite end of the data channel; estimating from said received pilot-embedded data matrix at least one channel state coefficient indicative of a characteristic of the data channel by a hybrid channel estimation; and recovering said space-time codeword data matrix “D” from said received pilot-embedded data matrix using said estimated channel state coefficient.

2. The method for data communication as recited in claim 1 , wherein said channel state estimating step includes the steps of: estimating said channel state coefficient from said received pilot-embedded data matrix by a first estimation and said predetermined data pattern; and updating said estimated channel state coefficient by a second estimation.

3. The method as recited in claim 1 , wherein the step of selecting the data-bearer matrix “A” and the pilot matrix “P”, comprises of: selecting the data-bearer matrix “A” with orthogonal rows and the pilot matrix “P” with orthogonal rows so that multiplication of one by the other results in a zero matrix.

4. The method as recited in claim 1 , wherein the step of allocating fractions of a fixed amount of transmission power further includes: minimizing the probability of error upper bound of a mismatch between said estimated channel state coefficient and perfect knowledge of said transmission channel state to said pilot matrix “P”; and scaling by a respective scaling factor each of pilot matrix “P” coefficients and said data bearer matrix coefficients in accordance with said power allocation.

5. The method as recited in claim 1 , wherein the pilot-embedded data matrix is formed by multiplying said space-time codeword data matrix “D” with the data-bearer matrix “A” which is scaled according to the transmission power and further adding said pilot matrix “P” which is scaled according to the transmission power.

6. The method as recited in claim 1 , wherein the hybrid channel estimation method includes the steps of: acquiring an initial channel coefficient vector estimate as the pilot-projected received vector using the maximum likelihood technique; and acquiring an improved channel coefficient vector estimate by performing an L-tap linear minimum mean-squared error estimator based on said initial vector and the previously estimated channel coefficient vectors.

7. A pilot-embedded data transmission and channel estimation method for a Multiple-Input Multiple-Output (MIMO) communication system comprising the steps of: forming a block codeword from a sequence of data matrix; modulating said codeword with a plurality of data bearing coefficients; adding to each symbol in said modulated codeword a value from a plurality of pilot values to form a pilot-embedded codeword; transmitting said pilot-embedded codeword; receiving said pilot-embedded codeword at a receiver; estimating from said received pilot-embedded codeword at least one channel state coefficient indicative of a characteristic of a corresponding data channel; recovering said sequence of data matrix from said received pilot-embedded codeword by said estimated channel state coefficient; allocating respective fractions of a fixed amount of power for transmission of said pilot-embedded codeword to each of said modulated codeword and said plurality of pilot values; allocating said fraction of power to said pilot data so as to minimize a probability of error upper bound of a mismatch between said estimated channel state coefficient and perfect knowledge of said characteristic of the data channel; allocating the remaining fraction of power to said modulated data matrix; and scaling by a respective scaling factor each of said plurality of data bearing coefficients and said plurality of pilot values in accordance with said power allocation.

8. The method for data communication as recited in claim 7 further including the steps of: providing a first plurality of antennas to the transmitter, each defining one end of a corresponding data channel; providing a second plurality of antennas to the receiver, each defining an opposite end of a corresponding data channel; and estimating in said channel state estimating step a channel state coefficient for all data channels defined by said first plurality of antennas and said second plurality of antennas.

9. The method for data communication as recited in claim 7 further including the step of selecting said data bearing coefficients and said pilot values such that when arranged to matrices consistent with modulation of and addition to said codeword by matrix operations, matrix multiplication of one of said matrices by the transpose of the other results in a null matrix.

10. The method for data communication as recited in claim 7 , where said channel state estimating step includes the steps of: estimating said channel state coefficient from said received pilot-embedded codeword by a first estimation and said predetermined data bearing coefficients; and updating said estimated channel state coefficient by a second estimation.

11. The method for data communication as recited in claim 10 , where said channel state information estimating step includes the steps of: providing as said first estimation a maximum-likelihood estimation of said channel state coefficient; and providing as said second estimation a linear minimum mean-square error estimation of said channel state coefficient given said maximum likelihood estimation of said channel state coefficient.

12. The method for data communication as recited in claim 7 , where said block codeword forming step includes the step of forming a space-time block codeword as said block codeword.

13. The method for data communication as recited in claim 12 further including the step of forming a vector from matrix of said received pilot-embedded space-time codeword prior to said channel state information estimating step.

14. A pilot-embedded data transmission and channel estimation method for a Multiple-Input Multiple-Output (MIMO) communication system comprising: a data encoder encoding data received at an input thereof into data matrix produced at an output thereof; a pilot embedder coupled to said data encoder and adding pilot data to said data matrix to produce pilot-embedded data matrix at an output thereof; a transmitter coupled to said pilot embedder at an input thereof and transmitting said pilot-embedded data matrix over a plurality of time slots such that said pilot data is transmitted in each of said time slots; a receiver coupled to said transmitter via at least one data channel, said receiver receiving through said data channel said pilot-embedded data matrix as modified by a characteristic of said corresponding data channel; a channel estimator coupled to said receiver and estimating from said pilot data added to each of said data matrix said characteristic of said corresponding data channel for each of said pilot-embedded matrix received; a data detector coupled to said channel estimator and recovering said data matrix from said pilot-embedded matrix in accordance with said estimated characteristic to produce at an output thereof estimated data matrix; and a data decoder coupled to said data detector and decoding said estimated data matrix in a manner complementary to said data encoder to reproduce said data.

15. The data communication system as recited in claim 14 , wherein said pilot embedder modulates said data matrix prior to adding said pilot data thereto.

16. The data communication system as recited in claim 15 , wherein said pilot embedder allocates power between said data matrix and said pilot data in accordance with predetermined criteria prior to said modulation of said data matrix.

17. The data communication system as recited in claim 14 , wherein said channel estimator performs a first estimation of said channel state and a second estimation of said channel state based on said first estimation.

18. The data communication system as recited in claim 14 , wherein said data encoder is a space-time block encoder.